Hydraulic transmission



' 7, 1953 F. "'M.' PERKINS HYDRAULIC TRANSMISSION 3 SheecsSheet 1 FiledFeb. 8, 1947 INVENTOR. I'RANK M PERKINS .AT TORHEY April 7, 1953 F. M.PERKINS 2,633,305

I HYDRAULIC TRANSMISSION Filed Feb. 8, 1947 3 Sheets-Sheet 2 VIZ 84'INVENTOR.

1 12A UK M PERKINS ATTORNEY April 7, 1953 Filed Feb. 8, 1947 3Sheets-Sheet 3 I x 38 V /0- i 2 r '0 43 25 30 44. 1 I /0 /9 '1 I; 3 1g:5

I 7/ a 2/ g /z a I r 9 i 9 INVENTOR.

' FRAMKMPERKINS o\ BY I 10 I I Z5- 3/ 3'2 34, J AI Patented Apr. 7, 1953UNITED STATES PATENT OFFICE HYDRAULIC TRANSMISSION Frank M. Perkins,Long Beach, Calif. Application February 8, 1947, Serial No. 729,431 I 9Claims. (01. 103 -120) This invention relates to new and usefulimprovements in power transmissions and has particular relation totransmissions using a positive pressure type of hydraulic pump or motorwith automatically controlled variable capacity to hydraulically driveor to be driven by another mechanism of fixed hydraulic capacity.

An object of the invention is to provide a positive drive hydraulicpower transmission including a variable speed ratio which is entirelyautomatically controlled so as to insure that a prime mover is alwaysoperating under its most desirable combination of drive shaft torque andangular velocity for theparticular power output required and that thetransmission output shaft torque is always sumcient to meet the loadrequirements.

Another object is to provide a novel means of continuously altering theflow capacity of a positivepressure hydraulic pump or motor.

An additional object is to provide a novel means for controlling thevarying or altering of the 110w. capacity of a positive pressurehydraulic pump or motor.

Other objects and advantages of the invention will become apparent froma consideration of the following detailed description taken inconnection with the accompanying drawings wherein a satisfactoryembodiment of the invention is shown. However, it is to be understoodthat the invention is not limited to the details disclosed but includesall such variations and modifications as fall within the spirit of theinvention and the scope of the appended claims.

In the drawings:

Fig. 1 is a top plan view of the present transmission;

Fig. 2 is a side elevational view thereof;

Fig. 3 is an enlarged view partly in plan and partly in section showinga four-way valve and its connection to a mechanism of fixed hydrauliccapacity;

Fig. 4 is a view looking from the top but with the upper portion of thecasing removed whereby to show in plan a control unit for a variablecapacity pump or motor, the view being taken as along the plane of theline 4- 4 of Fig. 5;

Fig. 5 is a view somewhat similar to but at right angles to Fig. 4, theview being taken as along the plane of the line 5-5 of Fig. 4;

Fig. 6 is a view partly in section and partly in elevation of saidvariable capacity pump;

Fig. 7 is a central vertical longitudinal sectional view through saidpump;

"Fig. 8 is a vertical sectional view taken as along theplane of the line8-8. Of Fig. 7

III

2 Fig. 9 is a vertical sectional view taken as along the plane of theline 99 of Fig. 7;

Fig. 10 is a vertical sectional view taken as along the plane of theline |0l 0 of Fig. 7

Fig. 11 is a vertical sectional view taken as along the plane of theline Illl of Fig. 5; and

Fig. 12 is an enlarged top plan view of a valve employed in connectionwith the mechanism for controlling the altering or varying of thecapacity flow of the variable capacity pump.

As used throughout this specification and claims, the word capacity asapplied to a hydraulic pump or motor unit refers to the vollume of flowper revolution of the revolving element or elements of said unit. Thepresent transmission is made up of several units which may be placed inany of various related positions although the accompanying drawings andpresent description disclose but one 01 the possible arrangements.

As shown herein, a variable capacity hydraulic power unit in the form ofa pump or motor I0 is provided and at one end, as the front end, of suchunit there is located a control mechanism generally designated II forcontrolling and varying the capacityof the pump or motor I0. As hereinshown, these units [0 and II are enclosed within casings l2 and i3 andthe lower portion of the latter constitutes a storage sump It for thehydraulic fluid. A four-way control valve is generally indicated at [5while at It is generally indicated a driven unit. While the units H),II, l'5-and lfiare shown in a more or less straight line arrangement, itwill be understood that the units I5 and It may be in some otherlocation since they are connected with one another and with the unitsIll and II only through piping constructions.

The manner in which the assembled units are supported on any suitablebase, block or the like is not material, but as here shown, the casingsl2 and l3 are provided with mounting lugs 9 for this purpose. The crankor drive shaft or the like of or from any suitable prime mover (notshown) .is connected to drive. shaft i1 comprising part of the controlmechanism H. Such connection may be made by bolting the prime mover.crank or a shaft driven from the prime mover to a plate or flange l8rigidly secured to or integral with the shaft ll. Because of thisconnection with the flange 18 or the like, the prime mover serves todrive the variable capacity pump l0 through the control unit II. Thedetails of this drivewill later appear.

Variable capacity pump Iii (see particularly Figs. 6-9) within thecasing l2 includes an elongated gear I 9 keyed as at on a shaft 2|having bearing at one end in an end wall or a separating wall or plate22 located between the casings l2 and I3 and secured in place as bymeans of the bolts 23 securing said casings together. The other end ofsaid shaft is mounted in a crosspiece 24 herein disclosed as integralwith the vertical side walls of the casing [2. In this connection itwill be understood that said crosspiece may be separately formed andbolted, welded or otherwise secured in place should such be desired.Further, it will be understood that any suitable construction of bearingmeans may be provided for the shaft 2|.

In spaced relation to, but parallel with, the shaft 2| is a stationaryrod 25 supported by the divider or separator plate 22 and a closure plte 26 located at the rear end of the pump and com-' prising, the rearend wall of the casing |2 The rod 25 is rigidly attached to both plates22 and 26 as by means of'nuts 21 and washers 28. Gaskets '29 under suchwashers are drawn against the outer sides of the plates 22 and 26 ontightening of the nuts 21 whereby to prevent leakage of oil or otherhydraulic medium from the housing about the rod 25.

Mounted on the rod 25 for sliding movement therealong is a gear 30 whichmeshes with the gear l9. Actually the gear 30 is mounted on bearings 3|whereby the gear is more freely slidable on the rod 25. These bearingsare shown as two spaced tapered, roller bearings, the outerraces 32 ofwhich are held'in place in recesses by threaded retainers 33. The innerraces 34 of said bearings are slidable along the rod 25 and'areprevented from rotating, and thus causing excessive wear on said rod, bymeans of lugs 35 (Figs. 8-1'0) which are integral with said inner racesand slide in a longitudinal groove 36' in said rod.

As shown best in Fig. 9, the pump l6 operates on the gear pump principleand therein it will be seen that rotation of the shaft 2| causingrotation of the gear l9 brings about rotation of the gear 36 with whichsaid gear l9 meshes. Oil or other hydraulic medium taken into the pumpcasing III as from a pipe 31'is carried around between the teeth ofthese gears and forced out into a. pipe 38 by the meshing of the gears.Since the gears are of fixed cross sectional dimensions the amount ofoil pumped per revolution of said gears is proportional to the distancemeasured parallel to their axes and over which distance said gears arein mesh. This distance and hence the effective gear mesh or capacity ofthe transmission is varied by sliding the gear 30 along the rod 25 aswill be hereinafter more fully considered.

Leakage of the hydraulic, fluid about or past the ends of the gears I9and 30 is prevented'by means now to be described. A'carrier 39'fits flatagainst the inner and forward end of the gear 30 which, as best shown inFig. '7, is heldto said carrier by means of an axial thrust bearing 40held in place and adjusted in tension by means of a ring 4| threadedaround the forward or inner end of a reduced diameter neck portion 42-of the gear. In its upper portion the carrierhas a round hole 43 boredtherethrough in concentric relation with the axis of the gear l9 andsuch hole is somewhat larger than the outside or major diameter of saidgear. Therefore, the carrier 39 and the gear 30 attached thereto mayslide parallel to the axes of the gears without in any way interferingwith the rotation of the gear IS.

A sealing ring 44 which has a close fit in but is rotatable in said hole43 is fitted with an axial thrust bearing 45 held in place and adjustedin tension by a bearing ring 45 threaded to the carrier 39. The innerface of the sealing ring 44 is flush with the inner face of that portionof the carrier 39 which is fiat against the forward end of the gear 30.Internally, the sealing ring 44 is provided with teeth (see particularlyFig. 10) cut to conform closely enough to the surfaces of the teeth ofthe gear I9, which said ring surrounds, to restrict oil leakage as muchas possible and still permit said ring to slide longitudinally ofsaidgear without excessive friction.

Thus, it will be understood that the ring 44 slide's'with the carrier 39which mounts it and also that sai d'ring is rotatable in the carrier oring ring 4'! is mounted in the casing l2 and is;

held in place by an axial thrust bearing 48 and a bearing retaining ring49 threaded to the casing Thus the sealing ring 41" isheldagainstany-slid ing movement but is rotatable with the gear 3| andthe latter may move through saidring.

The inner face of the sealing ring 41- is flat and is flush with theinner face of the crosspiece 24- against which the rear end of the gearl9 abuts in a fiat-to-fiat relationship. That part of the carrier 39which comes in contact with the outer peripheral surface of the gear I9slides in and conforms closely to a space 50 provided above thecrosspiece 24 as shownin Figs. 7' and 8. Thus very little oil ispermitted to leak past the cross piece 24 or the sealing ring 41.A'suitable packing 5| is provided about the shaft 2| where it passesthrough the platev 22 so as to prevent leakage of oil at such point. i

When the present mechanism is inuse, oil'is pumped from the variablecapacitypump Ii] out through the pipe 33 to the four-way valve 5- lihisvalve is manually operated or controlled by a rod 52 integral with orrigidly secured to a air of similar pistons 53 and located within the vvalve casing or housing 55'. By manipulation of therod 52 the pistons53, and 54 may be moved into any of four different positions to give aforward drive, a neutral drivea brake position and a reverse drive.

With this valve i5 in brake. position, as illustrated in Fig, 3,'oil orother hydraulic fiuid entering the valve casing from the pipe 38 passesdirectly into apipe 56 which is in communication with the interior ofsaid casing 55 adjacentthe.

two ends thereof, as at 5! and 58, Thus, See F 2) the pipe. 55 at itsvalve endis bifurcated or includes apair of portions or branches 5.9 and6t. communicating respectivelywith the openings 51 and58 from thecasing. Thepipe SHleads' directly back to the storage sump l4 inthelower portion of the casing is.

From this storage sump |4;,th.e oil or other by draulic fluid moves viathe pipe. 31 back into the pump In from whence the cycle is repeated.Sump I4 is sealed and is equipp d with tWO threaded plugs 62- and63whic'h are used for -fi ing and draining -re speotively.- A partition64 serves to seal ofi the sump i4 from theilppe chamber 65 within thecasing l3 and whichupp chamber comprises the chamber receiving thecontrol unit per se. A plug 66 providesfor drai ing'of the lubricatingoil from said upper cha n: ber 65. Pipes 6'! and 68 are arranged toConnect the interior of the valve casing 55 of the four-way valve [5with the driven unit [6.

- In the brake position of the valve 15, the terminals of pipes 61 and63 are blocked by the pistons 53 and 54 respectively and thus no oilflows through said pipes 61 and 68 to the driven unit 16 with which theyare connected. The forward drive of the unit. It is obtained by movingthe valve control rod52 as far as possible into the valvecasing In thisposition, oil pumped into the valve casing 55 through the pipe 38 passesto the driven unit It via the pipe 61 and returns to the valve via pipelit and hence into the pip 55, through the port 58 and branch 60, andback to the sump i i to be again drawn out through the pipe 31 by thepump iii. Thus; in this forward drive, the oil is flowing through thedriven unit IE5 from the pipe 6? to the pipe 68 The. reverse drive isobtained by moving the valve control rod 52 (see Fig. *3) further out ofthe housing or valve casin 55, thus causin the oil which enters from thepump through the line 38 to flow out through the pipe t8 through thedriven unit I6 and thence back through the pipe 61 into .the valv casing55 at the left side of piston 53 through port 51 to branch 5% andthrough the pipe 56 to the sump Hi. From the sump, the oil or otherhydraulic fluid is taken back into the pumpthrough the pipe 37 and thecycle continued. From the foregoing, it will be understood that theforward or reverse drive depends on the direction in which the oil orother fluid. under pressure or hydraulic medium is passed through thedriven unit it. Neutral drive is obtained by placing the valve rod 52 ina position half way between that of the forward and brake positionsabove described. In neutral position all pipes 38, 67, 68 and 56 arehydraulically connected to each other as oil is free to flow around thepiston 54 through a widened portion 69 of the valve casing 55, Leakageof the hydraulic medium from the valve l5 about the valve rod 52 isprevented by a packing or stuffing box arrangement including a packing10 held under pressure by a plug H threaded into a end plate 72 of thevalve casing. It will be understood that pipe connections other thanthose illustrated may be employed in making u the pipe arrangementsrequired by the present transmission. a

Any mechanical device or devices capable of converting hydraulic energyinto mechanical energy and operating under positive hydraulic pressuremay be used as the driven unit or units of this transmission. For thepurpose of illustra tion, the driven unit I6 is a simple gear type pumpor device. The same consists of a casin 73 receiving two meshing gears14 and 15 mounted in any suitable manner as on shafts l6 and ll of whichthe latter may protrude as shown to form 6 In the remainder ofthis'present description, the four-way valve i'd-will-be considered asin either forward or reverse drive position, the neutral and brakepositions being ignored. The effective speed ratio of the transmissionis here considered to be the ratio of angular velocities of the drivenunitoutput shaft 71 to the angular velocity of the revolving elements ofthe variable capacity pump [0 driven by the prime mover (not shown).Since the output shaft l! is ultimately driven by the variable capacitypump ID, the above mentioned ratio is the same as the ratio o thecapacities of the variable capacity pum it and the driven unit l6. Thismay be explained in equation form as follows: Effective speed ratio=Angular velocity of Capacity of variable driven unit (B. P. M.) capacitypump (gaL/rev.)

Angular velocity of Capacity of driven unit variable capacity pump(gal/rev.)

(R. P. M.)

Thus, the effective speed ratio can be changed by changing the capacityof the variable capacity pump.

As described herein, the pump I0 is used to hydraulically drive thefixed capacity hydraulic unit it. However, reversing this procedure andusing the unit it to drive-the device heretofore referred to as thevariable capacity pump I!) would not change in any way the novelty ofthe latter device or the control principles and mechanisms hereinafterdescribed. a Any type of hydraulic pump delivering positive pressure andhaving two revolving elements rotating on parallel axes may be convertedby similar methods to those described herein to serve as a variablecapacity pump. Thereafter, the employment of any such device would notchange the novelty of the variable capacity pump herein described.

For simplicity of illustration, a gear type pump (Figs. 6-10) isdescribed herein. The teeth of the pumping gears would ordinarily be ofthe nonpulsating flow type of helical gears with a small helix angle.However, for simplicity, straight spur gear teeth are shown in thedrawings.

At the respective. ends of the pump are cavities or spaces 18 in thefront end of the pump and F9 in the rear end of the pump. As previouslyexplained in connection with the pump, oil leakage from the cavitiesopening into the pipes 3'! and 38 to the cavities I8 and 19 at the endsof the pump is kept to a minimum. The small amount of oil (when oil isused as the hydraulic medium) that does leak past to the cavities l8 and'59 serves as a lubricant for the internal parts of the pump. Adifference in oil pressure, as between the end cavities 18 and 19 of thepump it], will cause the carrier 39 and the sliding gear 36 to moveparallel to the gear axes and change the capacity of said pump.

This change to give a differential in pressure as between the cavitiesor chambers 13 and l9 is accomplished as follows: a reversing valve 86(Figs. 4, 5, 11 and 12) is bolted or otherwise secured to the front wallor plate 22 of the pump housing I2 and is located within the casing orhousing l3 of a control unit. A high pressure by-pass pipe 8| connectsthe high pressure line or pipe 38 to the valve 80. Both internal endportions of said valve are connected by pipesor nipples 82 with the lowpressure sump i4. End cavity 18' of the pump I0 isconnected to the valve(Why a pipe 83 connected through the Wall or plateZZ whilea-pipe 64connects said valve with acsaa'oc 1 the chamber of cavity 19 in theother end portion of-- the-pumpcasing.

Valve 80 (see Fig. 12) consists of acylindrical housing- 85- containingtwo identical sliding pistons 85 and 81 integral or rigid with a pistonrod 88-. When said pistons are the neutral position in which they areshown in Fig. 12, no oil can flow to or from the valve. When, however,the piston rod 88 is pushed further into the valve 80 oil will flowthrough saidvalve-from the high pressure by-pass line 8-I to the pipe8-3 and-hence into the end cavity T8 of the pump. At this time, theopposite end cavity 19 of the pump is connected through the pipe 84,valve- 80 and one of the pipes or nipples 82 to the-low pressure sumpI4. This differential in oil: pres sure in the cavities 18 and 19 causedby connecting cavity'lil tothe. high. pressureoutlet pipe 38 from thepumpand the other" end. cavity of the pump to the low pressuresump 14will cause the. carrier 33 and the. gear 3!) to slide parallel tothe-gear axes and thus change. thecapacity of the pump It and hence theeffective speed ratio ofv the transmission;

Since the. application of pressure just described causes the carrier39." and. the gear 3| to move in a direction toreduce: the distance,measured parallel to the gearaxes, over which the gears I9 and 33 mesh,the capacity (volume flow per revolution) ofv saidpump is reduced. Hencethe elfective speed ratio of the transmission as previously suggestedis.- deereased. This ratio may be increased by withdrawing rod 88 as.far as possible from" the valve 89 and thus; permitting some of thehigh. pressure oil from pipe 38 to flow via pipe 8+ into the valve-80and hence out through-the pipe 8% into theend cavity #9 of. the pumpIll. At. the same: time, oil or other hydraulic medium is by-passed fromthe end cavity 18 of-pump Ill via pipe 83-throug-h valve and one of thenipples or pipes-82 into the'low pressure-sump.

A- novel feature of this invention is that the pump. Ill furnishes thehydraulic energy required for changing its. capacity. by having oil orother hydraulic medium .by-passed from thehigh-pressure pipe.- -3il.-(or the pump discharge. side). and the low. pressure (sump-r I41) sideof its main pump circuit to its. end cavities: through thepipes 83 and:and: the reversing, valve 80 The operation of thevalve80 may-be manualbut I have disclosed and will hereinafter describe anautomaticcontrolfor said valve for ohangingthe effective gear meshinthe pump. itaccording to principles to behereinafter set forth.

By definition, the. output power (brake horsepower) of a prime mover isthe product'of said prime movers output shaft. torque. (ft. 2:) andangular velocity (R. P. M.). multipliedby a suitable conversionconstant. Therefore, within the operating range of. any particular primemover there are a variety of possible combinations of. output shaftangular velocity and torque for each particular output power requirementof said prime mover. However, one of. these possible combinations-,-for: any particular power output, is consideredmore: desirable. than.any of. .the other combinations. of. torque. and velocity for that same.power output. The most desirable combination will, usually be chosen astheone with the greatest fuel economy that is the point at which theengine consumes the least fuel for that particular power output.However, if operating the engine at thispoint. will cause excessivemechanical wear, strain, or heating; some other 8i combination or outputshaft torqueand-angular velocity will be chosen-as'the' most desirable.

When said most desirable combinations are ploted for all possible poweroutput requirements of a given engine on a graph whose coordinatesareoutput shaft" torque and angular" velocity, a curve isformed. Anycombination of prime mover output shaft'torqu'e and angular velocitywhich does not fallon this curve-isnot the most desirable combinationfor the particular power output developed. In this invention, the saidcombination may be adjusted to fall on said curve" by changing thecapacity of pump Ill. Since pump Ill is driven by the primemover,decreasing said capacity will decrease the torque and thus cause anincrease-in the angular velocity of T the output shaft'of said primemover. Likewise, increasing the capacity" of pump I0 will increasesaiditorque and cause acorresponding decrease in said" velocity.

Asjust explained, whether a change in capacity of the: pump I0is'desirable andif so the direction in which the changeshould take placeis a matter of prime mover output shaft angular velocity and torque.According to thepresent invention, the required shift in thecapacityofthe' pump- Ill is accomplished by a manipulationof the reversing valvethrough the control mechanism generally'designated II.Aswill-lat'er'more fully appear, the operation is accomplished through acam by means of a overnor'unit' and torque gage mounted on the shaft IT(to which the. prime mover is connected) and thus respectively furnish adirect measurement of. said lprim'e mover torque and angular velocity.

As previously explained, the. output shaft of the prime moveror: ashaft. driven by: thev prime mover is. connected to rotate: the shaft.I'I' as by being bolted or? otherwise secured; to the plate I8. Thisshaft. I l is rotatably received. in andmounted by a bearing 89' formed;with one end of the housing I3 and in a housing-like member 90. Thishousing ormember 9'!) is rigidly'heldin place as. by beingv supportedfrom the sidewalls of housing. I3: bymeans of rigid bars9l;

On the shaft IT is. a governor; generally: designated- 92', including.forward. arms. 93 and 94" piv oted at 95 and 96; respectively, to acollar 9.1- fast on the-shaft I l. The rear governor arms 98 and areintegral with; weights Hit and. are pivotedto the forward. governor armsas at IOI-. Further, these-arms 98 and 99' are pivoted as'at I02 andIU3- to a sleeve I04 which is keyed to slide. along, and to rotate withthe shaft IT. A. compression: spring. I05- exerts a; force on: thesleeve I04 and at its other end: this spring; is held in place by awasher I06 backed up by a. pin I'M.

A collar H18 fits over: one end: portion; ofthe sleeve I64" and"is'mounted thereon by suitable anti-friction, bearings: as shown; Thus,said col.- lar is movable: along the shaft I-l with the sleeve I04 butthe-sleeve rotates within thewcollar and the latterdoesnot rotate;vSince. the spring. I05- resists. the: centrifugal force of the weights:I00, the positionof: collar HIB'is dependent. on'ly upon the: angular:velocity of; the shaft IT and thereby furnishes a direct measure of theangular velocity of the output. shait'of the prime-mover;

A- sun gear I09 (Fig; 111); is. fixed to the shaft I1. Arranged parallelwithsaid sun gear I09 is a disc or spider H0 fixed on the-shaft. 21which pinions I I I in positions meshing with the -sun 'gear' 9 and withthe teeth of an internal or ring gear H2. Thus, rotation of the sun gearI99 causes the four planetary pinions II I to roll around the inside ofthe ring gear H2 and thus rotate the spider or disc I I9 carrying saidplanetary pinions and fixed on the shaft 2I. Thus, it will be seen thatthe prime mover driving the shaftII functions to drive the pump I9through the planetary reduction gear just described.

The ring gear H2 is mounted on the housing 99 and rotation of the ringgear about said housing is limited by lugs I3 which are integral withsaid gear striking against a lug I4 which is integral with or secured tothe upper wall of the casing I3. A cam H5 is integral with the ring gearI I2 and rotation of the ring gear and cam is resisted by a coil springH6 which is secured at one end to the ear I I2 as at II! and at itsother end to a wall of the casing I3, as at H8. Thus, the rotaryposition of the gear H2 depends only upon the torque of the shafts I1and H. A cam rod H9 (Figs. 4 and 5) is held against the cam H5 by meansof a coil spring I29 acting against a lunger I2I which slides in theupper portion of the housing 99 and actually comprises a portion of rodH9 being integral therewith.

An upstanding lug I 22 is integral with the plunger I2I and thus theposition of said lug is dependent upon the prime mover output shafttorque. This is true since the lug is carried by the plunger I 2| theposition of which is determined by the cam I I5 integral with the ringgear H2 whose position depends upon the torque of the shafts I1 and 2Iand thus on that of the prime mover output shaft.

A rod or link I23 is pivoted to the collar I98 at I24 and a second rodor link I25 is pivoted to the lug I22 as at I26. Additionally, theserods or links at their other ends are pivoted to one another by rod I27passing through a cam slot I28 in a cam plate I29. Such plate is rigidwith a shaft I38 pivotally mounted at its respective ends in bearingelements I3I carried by the side walls of the casing I3. Rigid with theshaft I39 is a bar I32 arranged vertically and having its lower endportion connected with the outer end of the piston rod 88 by a pin andslot or other suitable connection, as suggested at I33.

With this construction it will be seen that any rotation or movement ofthe cam plate I29 about the axis provided by the shaft I39 will causesaid shaft to rotate and thus actuate the bar I32 so as to cause thepiston rod 88 to be moved off its neutral position whereby to supplyfluid under pressure to one or the other of the cavities I8 and ":9 inthe respective ends of the pump casing whereby to shift the carrier 39and the gear 39 to change the capacity of the pump as heretofore setforth in detail. The suggested rotation or pivotal movement of the camplate I29 will result when the pivot I 21 between the links I 23 and I25tends to a movement other than one following the contour of the camgroove or slot I28.

This cam slot I28 is so constructed that when the piston rod 88 is inits neutral position every possible position of the pivot I21 along saidslot, and hence the position of the collar I98 and the lug I22, andhence the prime mover output shaft angular velocity and torque are inthe most desirable combination, as previously determined and heretoforedescribed in detail, for the particular power output of the prime moverat that time. On a change in conditions, the automatic control deviceherein described will adjust the pump to meet such conditions, as forexample a change in resistance made by the output shaft I1 of the drivenunit I6.

Assume the prime mover to be driving the pump at a constant speedthrough the shafts H and 2| and the disclosed planetary reduction gear.Also assume pump I9 to be pumping oil or other hydraulic fluid throughthe driven unit l6 at a constant speed to meet the constant torqueresistance on the transmission output shaft 'II. Further, assume thatthe prime mover output shaft torque and angular velocity are in anycombination that will place pivot I27 in the cam slot I28 While the camplate I29 and hence the rod 88 of the reversing valve 89 are in theneutral position as previously described. In said position, no oil isby-passed to or from either of the end cavities I8 and 79. of the pumpand the pump remains locked in capacitythat is, the pump I9 is pumping afixed amount of hydraulic fluid per revolution.

Let us now suppose that an increased torque resistance is externallyapplied to the output shaft TI. This will tend to slow the angularvelocity of the gears I4 and I5 and thus increase the fluid pressure inthe pipes carrying oil Icetween the pump Ill and said unit I6. Thisincrease in fluid pressure acting within the pump I0 increases thetorque resistance of the gears I9 and 30 and the shaft 2|. Suchincreased torque resistance through the planetary reduction gear andthe'torque gage moves the lug I22 and at the same time causes shaft I!to decrease in angular velocity. Said decrease in angular velocity ofthe shaft I1 causes the collar I98 to be moved by the centrifugalgovernor 92.

The described movement of the collar I98 and the lug I22 causes thepivot I2! to exert pressure on a side of the cam slot I28 and thusimpart a rotary or turning movement to the cam plate I29. When thisoccurs, the rod I32 is actuated and actuates the piston rod 88 in adirection to cause the reversing valve 89 to by-pass hydraulic fluid insuch a way as to cause a decrease in the capacity of the pump I 0. Asabove explained, this is accomplished by having a higher pressure in thecavity 18 so as to move the carrier 39 and gear 39 toward the right, asviewed in Figs. 6 and 7.

This decrease in capacity of the pump I9 is due to the fact that less ofthe gears I9 and 30 are exposed to the high pressure oil being pumpedand thus there is a decrease in the torque resistance on the shaft 2I.This decrease will cause the lug I22 to tend to resume its originalposition and at the same time allow an increase in angular velocity ofthe shafts I1 and 2I whereby to cause the collar I98 to tend to resumeits original position under the influence of the governor 92. Theselatter movements of the collar Hi8 and the lug I22 cause the pivot I21to rock the cam plate I29 and hence the bar I32 and piston rod 88 backto neutral position and thus again lock the pump I9 in capacity until afurther change in capacity is initiated by prime mover output shaftconditions.

The changes having taken place as described, if there has been noadjustment of the fuel throttle of the prime mover, the latter will beoperating at its original output shaft torque and angular velocity.However, if the capacity of the pump I9 has been decreased, the drivenunit output shaft TI will be revolving at a lower velocity than beforethe adjustments were made in the pump by the control mechanism. Thepower output of the shaft 7'! is essentially unchanged, however, as saidshaft is meeting an increased essence 1'1 torque resistance. .If thisdecrease in transmis sion output shaft angular velocity is consideredundesirable, the operator of the prime mover or a throttle speedgovernor :of said prime mover can open wider the fuel throttle and thusincrease the output power.

A decrease in torque resistance :on the output shaft 11 of the unit I6would be handled entirely automatically in a similar manner to that justdescribed for an increase in said torque. Under such conditions, the camplate i229 would :be turned or tilted in the opposite direction and thepiston rod 88 shifted in the opposite direction so that the increase inpressure would take place in the cavity 79 of the pump. In thisconnection'it is noted that .in Figs. 6 and '7 the relationship of thegears l9 and 39 is that at which, or is substantially that at which, thepump is operating at maximum capacity.

From the above, it will be seen that the complete automatic control ofthe effective speed ratio of the transmission, based on engineperformance characteristics, is accomplished. The use of morecomplicated control mechanisms such as two reversing valves mechanicallyand hydraulically linked together to reduce shocks resulting from suddenchanges in the capacity "of pump It! would not change thenovelty of thecontrol principles herein described. Further, reducing the flow ofhydraulic fluid required to cause a change in capacity of the pump H byconnecting the pipes '83 and B l to small pistons, which would actuategear 39 axially in tead of connecting said pipes to the end cavities itand 19 of the pump l would not introduce any novelty.

As herein disclosed, onlythe :control mecha nism, with the exception ofits reversing'valve, contains moving parts whichare not immersed in oiland hence need additional lubrication. This could be supplied by any ofthe well known methods such as the splash or any of the various pressuresystems. If pressure lubrication of said parts is used, no additionaloil pump is necessary as the pressure may be supplied by the pump if! orthe prime movers lubrication pump forcing oil through the axial hole(not shown) in the shaft [1.

The variable capacity pump described herein need not be used with thecontrol mechanism herein disclosed. For example, the centrifugalgovernor, torque gage and reversing valve could be dispensed with andone or more springs inserted in an end cavity of the pump l0. Saidsprings would tend to slide gear 30 and carrier 39 so asto alwaysincrease the capacity of the pump Ill. The cavity containing saidsprings would be permanently hydraulically connected to the low pressureside of the main hydraulic circuitthat is, to pipe 56 or directly tosump I 4.

The opposite end cavity of the pump would be permanently connected tothe high pressure line carrying fluid from the pump to the driven unit.Thus, an increase in torque resistance on the transmission output shaft11 would cause an increase in pressure in the high pressure line andhence said pressure would drive carrier 39 and gear 38 against the force.of said springs toreduce the capacity of the pump It. This lattersystem takes no account of velocity and hence would probably be usedonly with a constant velocity prime mover.

Having thus set forth the nature of my invention, what I claim is:

1. In a hydraulic transmission, a pump including a pair .ofrctata'hlezmeshing elements having parallel axes, tmeanstmounting one of.said elements "for "axial movement :relative to the'other thereof tochange the efiective'gear mesh of said pump, va shaft tobe driven by aprime mover, a planetary reduction gear torque gage and a centrifugalgovernordevice mounted :on said shaft to'be driven by a prime mover,said planetary reduction gear connected to drive one of the elements ofsaid pump from said shaft to be driven by the prime mover, said pumphaving a cavity ateach of its endsadapted to receive fluid underpressure to shift one of the pump elements axially relative to the otherthereof to change the gear mesh of the pump, a hydraulic reversin valveselectively controlling the delivery of fluid under pressure to saidcavities, and cam means controlled by said torque gage and centrifugalspeed governor jointly and in turn controlling said reversing valve.

2. In a hydraulic transmission, a pump including a pair of elongatedmeshing gears arranged on parallel axes, a shaft mounting one of saidgears for driving the same, means mounting the other gear for axialmovement relative to the first gear to change the effective gear meshand thus the capacity of saidgpump, a control mechanism including ashaft to be driven by a prime mover, a planetary reduction gear betweensaid driven shaft and the first mentioned shaft and including a ringgear, a speed governor on said driven shaft, a cam movable in accordancewith turning movement of the ring gear of said planetary reduction gear,a spring resisting such movement of said cam and ring gear, a plungershiftable by said :camon movement of the latter, a cam plate, meansconnecting said cam plate with said speed governor and said plungerthrough a pin and cam 'slot connection, means mounting said cam platefor tilting movement when the combined movements of said plunger andspeed governor attached links cause the pin to press against a side ofsaid cam slot, and means controlled by the tilting movement of said camplate and causing axial movement of said slidable elongated gear tochange the effective gear mesh of the elongated gears of said pump andthus the capacity of the latter.

3. The hydraulic transmission as in claim 2 wherein the last named meansincludes a reversing valve and connections for delivering fluid underpressure selectively to the respective ends of said axially movablegear.

4. The combination as in claim 1 wherein the fluid for delivery to saidcavities is from the pressure side of said pump.

5. In a hydraulic transmission, a pump includ-- ing a .pair of rotatablemeshing elements having parallel axes, means mounting one of saidelements for axial movement relative to the other thereof to change theeffective gear mesh of said pump, a shaft to be driven by a prime mover,a planetary reduction gear torque gage and a centrifugal governor devicemounted on said shaft to be driven by a prime mover, said planetaryreduction gear having its output connected to drive one of the elementsof said pump and its input connected to said shaft to be driven by theprime mover, said pump having a cavity at each of its ends adapted toreceive fluid under pressure to shift one of the pump elements axiallyrelative to the other thereof to change the gear mesh of the pump, ahydraulic reversing valve selectively controlling the delivery of fluidunder pressure to said cavities, and means con- 13 trolled by saidtorque gage and centrifugal speed governor jointly connected to saidreversing valve.

6. In a hydraulic transmission, a pump including a pair of rotatablemeshing elements having parallel axes, means mounting one of saidelements for axial movement relative to the other thereof to change theeffective gear mesh of said pump, a shaft to be driven by a prime mover,a planetary reduction gear torque gage and a centrifugal governor devicemounted on said shaft to be driven by a prime mover, said planetaryreduction gear connected to drive one of the elements of said pump fromsaid shaft to be driven by the prime mover,-and means controlled jointlyby said torque gage and centrifugal speed governor for shifting one ofthe pump elements axially relative to the other thereof to change thegear mesh of the pump.

7. In a hydraulic transmission, a pump including a pair of rotatablemeshing elements having parallel axes, means mounting one of saidelements for axial movement relative to the other thereof to change theeffective gear mesh of said pump, a shaft to be driven by a prime mover,a planetary reduction gear torque gage and a centrifugal governor devicemounted on said shaft to be driven by a prime mover, said planetaryreduction gear connected to drive one of the elements of said pump fromsaid shaft to be driven by the prime mover, said pump having a cavity ateach of its ends, a hydraulic reversing valve selectively controllingthe delivery of fluid under pressure from said pump to said cavities,and means jointly controlled by said torque gage and centrifugal speedgovernor connected to said reversing valve.

8. In a hydraulic transmission, a unit including a pair of rotatablemeshing elements having parallel axes, means mounting one of saidelements for axial movement relative to the other thereof to change theeffective gear mesh of said unit, a shaft to be driven by a prime mover,a torque gage and a centrifugal overnor device mounted on said shaft, adriving connection between said shaft and one of the elements of saidunit, and means controlled jointly by said torque gage and centrifugalspeed governor for shifting one of the unit elements axially relative tothe other thereof to change the gear mesh of the unit.

9. In a hydraulic transmission, a hydraulic power unit having a variablecapacity and including a driven element and a movable capacityvaryingelement, a shaft drivable by a prime mover, a driving connection betweensaid shaft and said driven element, a movable torque sensitive meanscooperatively connected between said shaft and said driven elementsensitive to torque differential between said shaft and driven elemerit,a movable speed sensitive means cooperatively connected to said shaft,and movable means operatively connected to and controlled jointly bysaid torque and speed sensitive means and operatively connected to saidcapacity-varying movable element to activate the latter according to apredetermined pattern.

FRANK M. PERKINS.

REFERENCES CITED The following references are of record in the file ofthis'patent:

UNITED STATES PATENTS Number Name Date 788,848 Riegel May 2, 19051,216,243 Marsh Feb. 13, 1917 1,775,856 Hauser Sept. 16, 1930 1,787,565Brown Jan. 6, 1931 2,149,326 Wilkin Mar. 7, 1939 2,291,011 Vickers July28, 1942 2,382,389 Benedek Aug. 14, 1945 2,406,965 Orr Sept. 3, 1946

